1. Field of the Invention
The present invention relates generally to battery packs, and more particularly to the construction and operation of high energy battery packs, particularly in environments where multiple battery packs may be used.
2. Description of the Prior Art
Batteries and battery packs in electrically operated devices are commonplace. Devices such as flashlights and remote controls are often powered by a single-use AA or AAA cell, known as a primary (non-rechargeable) cell, which must be replaced when depleted.
In devices such as cell phones, video cameras, and laptop computers, individual secondary (rechargeable) cells are packaged together in a battery pack which can go through multiple charge—discharge cycles. In many of these devices, the battery pack may be removed and replaced by the user.
A given battery pack has a specific design capacity which defines the operating time of the device it powers. As a result, a user of a device powered by such a battery pack must typically recharge or replace a depleted battery pack for extended device operating times, or power over time.
Some laptop computers are configured to contain two separate battery packs. While this does provide for longer laptop operating time, the two battery packs are used sequentially, with one battery pack being used until it is depleted, the laptop then switching to using the other battery pack.
The Giant® Twist Freedom electric bicycle can carry one or two battery packs, using one battery pack at a time to power an electric motor on the bicycle. While the ability to carry two battery packs extends the operating range, the Giant Twist Freedom requires the rider to manually select one battery pack to operate the motor, and then manually select the other battery pack when the first battery pack is depleted. When a battery pack is depleted, it must be removed from the bicycle for charging. Charging two battery packs at the same time requires two chargers.
What is needed is to be able to use multiple battery packs in a way that gives the user longer operating time and more operating power than is available from using a single battery pack at a time.